Carburetor



Aug. 16, 1932.

J. scHwEiss 1,r872,509

CARBURETOR Filed July 6, 1929 JOSEPH SCHWE/ss //V VEN TOE WAM? HTToe/YEY Patented Aug. 16, 1932 ,UNITED STATES PATENT OFFICE JOSEPH SCHWISS, 0F ST. LOUIS, MISSOURI, ASSIGNOB TO CARTER GABBUBETOB 00B- POBATION, OIF ST. LOUIS, MISSOURI, A CORYORATION F DELAWARE CABBUBETOB Application 'le l'ulyA 8, 1928. Serial lo. $76,878.

This invention relates to carburetors and more particularly. to suction operated spray carburetors of the type in whichthe fuel is lifted or sucked into the mixing chamber by the suction of the engine. In carburetors of that type, it is usual to providesome means for restrictin the admission of air to the mixing cham er when it is. desired to start the engine; otherwise thecomparatively low Z0A suction developed by the engine when it is rotated at a low speed by the starting device would be insuiieient to draw a proper quantity of fuel into the mixing chamber.

It often happens that when carburetors of 1l this type are adjusted for starting, that is 'to say, when the air inlet to the mixmg chamber is restricted, the engine will start, but fail .to run. This is due to the fact that the operator is unable to open the choke or other re-c 2o striction to the air inlet quick enough after the engine starts tov fire, with the result that v an over-rich mixture is drawn into the engine by the comparatively high suction which is produced as soon asY the yengine starts to run under its own power.

` It will be understood that the electric or other starting devices which are used for starting internal combustion engines are ca'- pable of turning the engine over only ata comparatively low speed, say, thirty to lifty revolutions peraminute. On the other hand,

the lowest speed at which many engines willrun under their own power may be two or three hundred revolutions per minute. It

85 will be obvious that the air inlet must be much more highly restricted in order to; produce an appreciable ysuction at the low speed delivered -by the starter,'than would be suitable for operation at the comparatively high speed at 40 which the engine runs under its own power.

in the art that the term air valve carburetor implies a suction operated spray' carburetor having one or more air passages which are normally closed by a suction operatedl valve,

this valve usually controlling the so-called` auxiliary air passage which does not usually enclose the main jet of the carburetor. The term plain tube carburetor will be under,- stood to imply one in which no suction operated valve is employed under normal operat- I ing conditions, although such a valve may be used, as in the case of the present invention, .for operation under abnormal conditions such as starting.

As' is well-known to those skilled in the art, the air valve type of carburetor is highly desirable for startlng purposes on account of the comparatively lowstarting speed and the great variation in suction from cranking speed to the speed at which the engine is operated for warming up urpo'ses. The suc- `tion operated air valve, w ether controlled by gravity or spring, is capable of nicely adjusting the air inlet to give a suitable mixture. On the-otherhand, the air valve carburetog` is not. desirable for high speed'running purposes, as the drag of the air valve on the air stream flowing into the carburetor reduces the amount of air which the carburetor will low at maximum speed, a diiculty which is not present in plain tube carburetors.

It is an object of this invention to produce a carburetor having automatic means. for at least partially relieving the restriction at the entrance to the mixing chamber as soon as the engine begins to run under its own 5ower. `Another and further object of this invention is to produce a simple and 'easily man- ".ufactured carburetor having means for suitably`restricting the air inlet for starting purposes and for automatically regulating the restriction after the engine has started.'

Other objects of the invention will appear from the following specification and the ac-V companying drawing, referring to which:

, Figure 1 is a viewpartially in section of acarburetor constructed according to my .iu-` l vention.

Figure 2 is a view similar to Figurel, ex-

parts are in a different operatstricting member 6 which is held in position by a pin 7 or other suitable means. The body member has an annular surface 8 which is provided with a suitable gasket to receive the upper edge of the cup-shaped fuel bowl 9. The body member also has adownwardly extending portion 10 to which the bowl is attached by a nut 11, as shown. The fuel is supplied to the bowl by conventional means (not shown) and maintained` at a constant level therein by the usual float 12. The upper part of the extension 10 is provided with a downwardly extending recess 13 which is screw threaded at 14 to receive a standpipe4 or primary mixing chamberl 15. A main jet member 16 of conventional construction supplies fuel lfrom the bowl to the standpipe. The jet 16 terminates at or near a restricted portion or Venturi 17 in the standpipe. AThis venturi or restricted portion is between the main air inlet port 18 for the standpipe and the discharge outlet 19 whichis at or near the throat of the Venturi member 6. The standpipe is provided with one on `more auxiliary air ports 20 which normally permit the entrance of a quantity of air in addition to that entering through the main air inlet 18. The-usual idlingtube 21 is provided, and this communicates at its lower end with the fuel bowl and at its upper end with a bore 22 in the body4 member of the carburetor`. Thisbore discharges at the idling port 23` and is regulated in `a conventional manner by the regulating screw 24. An air bleed duct 25 is provided for the idling tube and also a second air inlet port v26. The port 26 opens at or near the throat of the Venturi, as shown. A conventional butterfiy throttle 27 is mounted on a shaft 28. This throttle is mounted inthe passageway 5 at the outlet of the main mixing chamber 29. The standpipe 15 is of considerably smaller diameter at its upper end than the 4throat of the venturi 6, and the annular space around the body ofthe standpipe forms a secondary air inlet 30 in addition to the primary air inlet 18, the auxiliary air ports 20. and the bleed 31 which leads to the accelerating well 32. For starting purposes, it is desirable to close the secondary air passage 30. and for vthis purpose I provide a choke 33 having an operating collar 34 which is operated by the yoke 35. The yoke is mounted on the choke operating shaft 36 The choke is rovided with an outwardly and downwar ly extending portion to close against the end of the venturi V6, as indicated in Figure 2, A plurality of ports 37 are formed in the choke, and

these are normally closed by a valve 38 which is slidably mounted on the choke substantially as shown and retained in position by a ring and groove construction 39, as indicated. The valve'member 38 is freely slidable up and down on the choke, but not removable therefrom in ordinary operation.

l Theoperation of the device is as follows:

The carburetor being attached by means of the ange 4 to the intake manifold of the internal combustion engine, the shaft 36 is operated to move the cone 33 into the position shown in Figure 2. This closes the annular passageway between the throat of the venturi and the top of the standpipe and also closes the ports 20.

When the engine is rotated bythe starting means, air is drawn into the primary mixing chamber through the ports 18 and 31. This air passing up through the venturi 17 and co-actlng with the suction from the engine draws fuel from the jet 16 and mixes with it in the primary mixing chamber or standpipe "15. The mixture thus formed is drawn up into the intake manifold past the throttle valve 27 which is moved to the position shown in Figure 2 for starting. This is for the purpose of permitting the comparatively low suction developed by the engine at starting to act on the from.

The suction developed by the engine is sufieptly relieved by -air entering the ports 18 and 31 so that the weight of the valve member 38 is suiiicient to keep the ports 37'in closed position as long as the engine is turning over at a comparatively low speed, but as soon as the engine begins to run under its own power,

-it runs faster and the increased suction immediately liftsLthe valve 38 to a position shown by the dotted lines in Figure 2, permitting additional air to enter through the ports 37 and thus forming a suitable mixture for warming up purposes. After the engine is suitably warmed up, the shaft 36 is rotated to the position shown in Figure 1, thus fully opening the annular passageway 30 between the throat of the main venturi and the upper part of the standpipe 15 after which the throttle 27 may be adj usted at will and the engine operated in the usual manner.

I claim:

1. In a carburetor, a main venturi, a standpipe forming a primary mixing chamber and discharging at the throat of said main venturi, said standpipe being smallerthan the throat of said venturi and concentric therewith, an air inlet for said standpipe, an annular valve slidably mounted on said standjet 16 to withdraw fuel therepipe adapted to close against the end of said venturi, a by-pass formed in said annular valve, and a suction operated valve for temporarily controllin said by-pass.

2. In a plain tu carburetor, a nmary air passage constantly in communication wit the atmosphere, a secondary air passage normally in communication with the atmosphere, manually operated means comprising an annular valve surrounding said rmary air passage for temporarily closingt e secondary air passage for starting purposes, a by-pass for said closing means, and suction operated means controlling said by-pass.

3. In a carburetor o main venturi, a standpipe discharging substantiallyat the throat of said venturi, said venturi being of larger diameter than the standpipe so as to leave an annular passageway therearound, an annular valve slidably mounted on the standpipe for closing said passageway, a by-pass through said annular valve, and means operated by gravity for controlling said by-pass.

4. In a carburetor, a vertically disposed main venturi, a standpipe concentric with said venturi, said venturi being of larger diameter than said standpipe so as to leave an annular passageway normally open throu h A the venturi, an annular valve slidable on said standpipe and movable into said annular passageway to obstruct the same, a by-pass through said valve, and a displaceable closure for said by-pass.

5. In a carburetor, a vertically disposed main venturi, a standpipe concentric'with said venturi, said venturi being of larger diameter than said standpipe so as to leave an annular passageway normally open through the venturi, an'annular valve slidable on said standpipe and movable into said annular passageway to obstruct the` same, a by-pass through said valve, a displaceable closure for said by-pass, said closure being normally held in position to close said by-pass by its own weight and being movable by suction to open said passageway. l

In testimony whereof, I alix my signature this 26th day of June, 1929.

JOSEPH SCHWEISS.

the plain tube type, a Y 

